(Test) Dummy VGA Dongle with Win7: Three Radeon HD 5770 and a Single Monitor (VGA Hack)

I recently played with multi-GPU and I needed to test one my GPU tools on three Radeon HD 5770 at the same time (no CrossFire). Under Windows 7, a graphics card is disabled by Windows if it’s not connected to a monitor. Not really convenient if you need to test several graphics cards and if you have only one monitor.

If you look at the CCC (Catalyst Control Center), you’ll see the primary card (enabled) and two disabled cards:

Catalyst Control Center, primary card enabled

Catalyst Control Center, second and third cards disabled

Same thing with the GPU Caps Viewer OpenCL panel, only the first GPU (Juniper) is listed:

The second and third cards are disabled (for APIs like OpenCL, CUDA, etc.) but are still visible in GPU monitoring tools like GPU Shark:

The fan keeps spinning so I would say so. They would need a special switch on the card’s power input to be able to turn a card off completely but they don’t bother as it is not like you can hot swap PCI cards.

Hmm… So i presume it’s just in idle state. Thanks.
I guess if i need to test some app on Nvidia card and on ATI card, to ease the process i can simply insert both cards in my PC and then just switch the monitor to one or another and simply relaunch the application?